Like others, my curiosity was piqued by a TheoryofReddit post. Hubski certainly has felt like a great alternative to reddit so far, although I would say there is a little bit of a learning curve.
There is a learning curve but once you "get it" it is really easy to navigate and actually makes more sense than reddit in a lot of ways. The biggest advantages of not having subreddits is you can avoid the people that post shit content. I follow everybody and then unfollow them when I start noticing that I'm not really into their content. It's worked out pretty good so far, although this explosion of new users is seriously hindering this strategy. In theory, Hubski can be like twitter in the sense that people who like to post X content can have a little cluster, while not affecting the rest of the users on hubski. For example, there are a ton of people on twitter who solely tweet "SMH DIS BOY IS CRAY CRAYYYYYY!" but I never have to see them.